Don't get ivory. You'll never wear it again. I did, and it was a waste. My wedding shoes were also fug. I should've looked for SHOES, not WEDDING shoes.
I don't think the ballroom dancing style shoe is the most attractive BUT I think they will look fine under a dress and they should be nice and comfortable to be standing all day and dancing in. Maybe look for some actual ballroom dancing shoes if that's the stlye you like - they will probably be nice and padded.